Method for pouring liquid metal using electromagnetic pump

ABSTRACT

Molten metal is poured from a receptacle through a discharge orifice at a substantially constant predetermined discharge rate. Metal is transferred from the receptacle to the orifice at a rate in excess of the predetermined discharge rate to completely cover the orifice with a predetermined head of liquid metal. Metal transferred to the orifice from the receptacle in excess of the predetermined discharge rate is returned to the receptacle so that the predetermined head is maintained substantially constant.

. United States Patent Eickelberg A 51 Sept. 24, 1974 [75] Inventor: Henry L. Eickelberg, Port Washington, Wis.

[73] Assignee: Modern Equipment Company, Port Washington, Wis.

[22] Filed: Feb. 14, 1972 [21] Appl. No.: 226,114

[52] U.S. Cl 222/1, 222/383, 417/50 [51] Int. Cl B22d 37/00 [58] Field of Search 222/1, 383, DIG. 2, DIG. 12, 222/DIG. 15; 164/337; 417/50 [56] References Cited UNITED STATES PATENTS 3,554,670 1/1971 Von Starck et a1 222/DIG. 2 3,610,600 10/1971 Schnake 266/34 3,612,720 10/1971 Von Starck 222/DIG. 2 3,713,639 1/1973 Von Starck et al. 417/50 UR X FOREIGN PATENTS OR APPLICATIONS 969,953 12/1950 France ..222/DIG.15 2,061,168 6/1971 Germany ..417/50 Primary Examiner-Robert B. Reeves Assistant ExaminerDavid A. Scherbel Attorney, Agent, or FirmMeyer, Tilberry & Body [5 7] ABSTRACT Molten metal is poured from a receptacle through a discharge orifice at a substantially constant predetermined discharge rate. Metal is transferred from the receptacle to the orifice at a rate in excess of the predetermined discharge rate to completely cover the orifice with a predetermined head of liquid metal. Metal transferred to the orifice from the receptacle in excess of the predetermined discharge rate is returned to the receptacle so that the predetermined head is maintained substantially constant.

5 Claims, 4 Drawing Figures PATENTED 3924B smiurz m3 W. WI

PAI ENIEB sirzmsn SHEET 20f 2 mm mm mm mm METHOD FOR POURING LIQUID METAL USING ELECTROMAGNETIC PUMP BACKGROUND OF THE INVENTION This application relates to the art of pouring liquid metal, and more particularly to pouring molten metal from a receptacle through an orifice. The invention is particularly applicable to an apparatus wherein an electromagnetic induction field is used to move the metal and will be described with particular reference thereto. However, it will be appreciated that the invention may be carried out with other transfer means for transferring metal from the receptacle to the orifice.

There are many known arrangements for attempting to successively transfer substantially equal volumes of molten metal from a receptacle to successive molds. One known arrangement for accomplishing this includes a pressurized receptacle. The pressure in the receptacle is successively raised and lowered in order to successively pour substantially equal volumes of metal. Variations in the amount of metal in the receptacle, and small variations in pressure, make it very difficult to successively pour substantially equal volumes of metal with great accuracy.

Other arrangements include a mechanical pump driven by an electric motor. With certain molten metals at high temperatures, mechanical pumps rapidly deteriorate. Fluctuations in voltage applied to the driving motor cause the pump to operate at varying speeds so that it is difficult to make successive pours of equal volume with great accuracy.

Other known arrangements for pouring molten metal include a receptacle having an upwardly inclined discharge passage. An electromagnetic induction field is used for moving the metal up the discharge passage. Known apparatus of this type is disclosed in U.S. Pat. Nos. 3,515,898 issued June 2, 1970; 3,534,886 issued Oct. 20, 1970; and 3,554,670 issued Jan. 12, 1971. In apparatus of this type, the upwardly inclined discharge passage terminates at a discharge weir. There are many different formulae for determining the rate of flow over a weir. In general, a somewhat different formula is used for each different shape of weir. Regardless of the shape of the weir, the rate of flow over a weir is proportional to the metal depth over the lip or crest of the weir raised to a power greater than one. Therefore, a small change in the depth of liquid flowing over the weir greatly changes the flow rate.

In electromagnetic apparatus of the type described, it is extremely difficult to adjust the electromagnetic induction field for moving metal from the receptacle up the discharge passage at such a rate that the depth of metal over the weir will remain substantially constant. In practice, variations in the depth of metal flowing over the weir will vary and this greatly changes the flow rate. In apparatus of the type described, it is desirable to discharge metal at a substantially constant rate for a predetermined period of time so that equal volumes of metal may be discharged into a mold or the like in successive pours. Small variations in the depth of metal flowing over the weir causes a major change in the flow rate due to the fact that the flow rate is proportional to the metal depth raised to a power greater than one.

' This makes it practically inpossible to make successive accurate pours of predetermined volumes of metal over substantially equal periods of time.

SUMMARY OF THE INVENTION Metal is poured from a receptacle through a discharge orifice at a substantially constant predetermined discharge rate. Metal is transferred from the re- The improved apparatus and method of the present invention may be used with a mechanical pump or with pressure to define the transfer means for transferring the metal from the receptacle to the discharge orifice.

In accordance with a preferred arrangement, apparatus of the type described has an upwardly inclined discharge passage which terminates at a discharge orifice instead of a weir. Flow through an orifice is proportional to the square root of liquid depth over the orifice. Therefofore, small variations in the depth of metal over the orifice vary the flow rate in a more insignificant manner proportional to the square root of the variation in depth.

In accordance with the preferred arrangement, the electromagnetic induction field is operated to move metal from the receptacle up the discharge passage at a sufficient rate for completely covering the discharge orifice with a predetermined head of liquid metal. This predetermined head is maintained substantially constant so that metal flows through the orifice at a substantially constant predetermined rate.

In the preferred arrangement, the induction field is operated to move metal up the discharge passage at a rate in excess of that required to maintain metal flowing through the orifice at the desired predetermined rate. Metal in the discharge passage then includes a lower level moving upward under influence of the induction field and an upper level moving downward under influence of gravity. The predetermined head over the discharge orifice is then maintained by having excess metal moved up the discharge passsage under influence of the induction field flow back down in an upper level under influence of gravity.

In accordance with another aspect of the device, the induction field is alternately energized and deenergized at predetermined intervals of time for successively discharging substantially equal predetermined quantities of metal through'the discharge orifice.

In accordance with another aspect of the device, the discharge orifice is provided with a selectively openable and closable stopper. Selectively opening and closing the stopper at predetermined intervals of time successively discharges substantially equal predetermined quantities of metal through the discharge orifice. The induction field may then be maintained in operation at all times.

It is a principle object of the present invention to provide an improved apparatus and method for pouring liquid metal.

It is another object of the present invention to pour molten metal at a substantially constant rate through a discharge orifice by transferring metal to the orifice at a rate in excess of the discharge rate so that a substantially constant head is maintained over the orifice and excess metal is returned to a receptacle.

It is also an object of the present invention to provide an improved apparatus and method for pouring liquid metal at substantially constant rate while using an electro-magnetic induction field to move the metal.

It is an additional object of the present invention to provide an improved apparatus and method for pouring liquid metal by using an electromagnetic induction field, and without requiring accurate energization of the induction field to pour metal at a constant rate.

It is a further object of the present invention to provide an apparatus and method for pouring liquid metal in a more accurate manner than was heretofore possible.

BRIEF DESCRIPTION OF THE DRAWING The invention may take form in certain parts and arrangements of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawing which forms a part hereof;

FIG. 1 is a side, elevational cross-sectional view showing the metal pouring appparatus having the improvement of the present invention incorporated therein;

FIG. 2 is a cross-sectional elevational view looking generally in the direction of arrows 2--2 of FIG. 1;

FIG. 3 is a view similar to FIG. 1 showing an alternative arrangement; and

FIG. 4 is a view similar to FIGS. 1 and 3 showing another alternative arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, wherein the showings are for purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting same, there is shown a receptacle A in which liquid or molten metal B is contained. Receptacle A may be heated in a known manner for maintaining metal B in a liquid or molten state. A removable cover may be provided for receptacle A if so desired to minimize heat losses from metal B due to radiation.

Receptacle A includes an outlet communicating with an upwardly inclined channel or discharge passage 22 having an upwardly inclined bottom wall 24. Discharge passage 22 is closed at its outer end by wall 26. Bottom wall 24 of discharge passage 22 terminates at a vertical discharge orifice having a substantially circular cross-sectional configuration. It will be recognized that a discharge orifice having other crosssectional shapes may also be used, and it will be further recognized that orifice 30 could extend horizontally through end wall 26 adjacent bottom wall 24. 68

In one arrangement, an electromagnetic inductor C, which is shown only schematically, is positioned directly beneath bottom wall 24 of discharge passage 22. The necessary voltage to energize inductor C may be produced by generator D which is connected with inductor C through transformer E. Although generator D and transformer E are illustrated only schematically for simplicity, it will be recognized that these are threephase devices.

In the arrangement shown, receptacle A contains molten metal B having its upper surface at a level some what higher than the bottom portion of outlet 20. However, it will be recognized that receptacle A is capable of holding sufficient molten metal to bring the surface level up to a higher point such as represented by a maximum level line 34.

It will be reocgnized that inductor C may take many forms. In one arrangement, inductor C may comprise a three-phase winding having a plurality of pole spans or polar divisions represented by shadow lines 36. The lower end of inductor C is connected with transformer E by a line 40. Another line 42 connects transformer E with a pole span of inductor C short of outer end 44 of inductor C. Therefore, the main portion of inductor C between lines 40 and 42 is energized when main switch 46to generator D is closed. It will be recognized that the electrical connections illustrated are only schematic for simplicity of illustration and that connections from the source of energy to the three-phase winding would actually be made every 120 electrical degrees of winding spacing.

The remaining portion of inductor C, extending between line 42 and terminal end 44, is connected with transformer E through line 48 which includes normally open switch 50. It will be recognized that line 42 is connected with transformer E at a point which'energizes inductor C at a lower energy level between lines 40 and 42 as compared to full energization of inductor C when switch 50 is closed.

In operation of the device, the electromagnetic induction field produced by energization of the main portion of inductor C between lines 40 and 42 is sufficient to raise metal from receptacle A only to around point 58 which is above maximum metal level 34 in receptacle A. When it is desired to pour a predetermined quantity of metal into a container or mold, switch 50 is closed. This energizes entire inductor C from its inner end 60 to its outer end 44 through lines 40 and 48 at a higher energy level than that provided to that portion of inductor C connected with lines 40 and 42. Metal then rapidly moves up bottom wall 24 of discharge passage 22 and covers outlet nozzle 30 with a predetermined head 64 of molten metal. Metal will then be discharged through orifice 30 at a predetermined substantially constant rate proportional to head 64. Inductor C is energized at an energization level in excess of that required to maintain a predetermined constant flow through orifice 30. Therefore, a metal in discharge passage 22 during a pouring operation includes a lower level 66 moving upward of bottom wall 24 under the influence of the induction field and an upper level 68 moving downward on the lower level under influence of gravity. With this arrangement, fluctuations in the strength of the induction field will have little effect on the rate at which metal is discharged through orifice 30.

In one arrangement, for a passageway 22 having a rectangular cross-section and a width of 3 1/4 inches, inductor C has been energized for transferring metal from receptacle A to orifice 30 at a rate of 8 /2 pounds per second. This maintains a head 64 of 5 inches, and metal flows through orifice 30 at a rate of 2.2 pounds per second. With passageway 22 inclined upwardly at 18 degrees, metal flows back into receptacle A in an upper layer at a rate of 6.3 pounds per second. In this example, circular orifice 30 has a diameter of 3/4 inch.

Variations in the rate at which metal is pumped up discharge passage 22 by inductor C will not vary head 64 significantly. For example, energization of inductor C to move metal upward at a slightly greater or lesser rate than in the example given will simply cause metal in upper layer 68 to flow back down under influence of gravity at a greater or lesser rate without significantly changing head 64. In addition, small changes in head 64 produce very small variations in the flow rate through orifice 30 because the flow rate is porportional only to the square root of depth 64. After a predetermined period of time, a predetermined volume of metal will have been discharged through orifice 30 because it is flowing therethrough at a substantially constant rate. Switch 50 may then be opened. All metal in discharge passage 22 between points 44 and 58 will then rapidly flow back down into receptacle A under influence of gravity, and upper level 68 will also flow back down into receptacle A. Metal flow will then take place only between points 40 and 42. It will be recognized that the arrangement described provides for alternate energization and deenergization of the induction field at predetermined intervals of time for successively discharging substantially equal predetermined quantities of metal through orifice 30.

In accordance with another arrangement, a stopper 70 may be provided for selectively opening and closing discharge orifice 30. Stopper 70 may be connected with a reciprocating rod 72. Rod 72 has a pin 76 extending through a slot 78 in rod 80 which is pivoted at 82. A solenoid 84 has a rod 86 connected with another slot 88 in rod 80 by pin 90. Solenoid 84 may be connected with a timer 92. A spring 94 may be provided for normally biasing rod 80 in a counterclockwise direction about pin 82 for normally placing stopper 70 in orifice 30 to stop flow of metal therethrough. Energization of solenoid 84 at predetermined intervals of time by timer 92 may move solenoid rod 86 downward to pivot rod 80 clockwise about pin 82 for raising stoppers 70 out of orifice 30 to permit flow of metal therethrough. With this arrangement, entire inductor C from outer end 44 to inner end 60 may be constantly energized at its high energization level for providing excess metal flow to maintain predetermined head 64 over orifice 30. Selective opening and closing of stopper 70 by timer 92 at predetermined intervals of time will permit successive accurate pours of predetermined volumes of metal.

In a preferred arrangement, discharge passage 22 is somewhat channel-shaped and bottom wall 24 has a substantial width. Slight variations in the rate at which metal is moved up passage 22 by inductor C will then produce very insignificant changes in head 64 because the substantial width of upper level 68 will allow slightly greater or lesser flow with minor fluctuations in head 64.

Instead of having excess metal returned in an upper level in the discharge passageway, it will be recognized that it is possible to have a separate return passage or return means to the receptacle for the excess metal. Excess metal would then overflow into the separate return passage when the predetermined head is reached. One arrangement for doing this is shown in FIG. 3. An outlet conduit 102 has an inlet 104 communicating with receptacle A and an outlet 106 discharging through end wall 26 against baffle 107 above orifice 30 and above normal head 64 which is being maintained. A carbide pump P in conduit 102 is driven by an electric motor for transferring metal from receptacle A to discharge orifice 30 at a rate in excess of that required to maintain the predetermined discharge rate. The desired head 64 will then be developed and maintained while excess metal simply flows down passageway 22. It will be recognized that it is possible to use this arrangement with the previously described stopper so that pump P is constantly delivering metal. However, it will be recognized that this arrangement may be used without a stopper and that the motor driving pump P may be successively energized and de-energized while making successive pours of substantially equal volume. It will be recognized that the apparatus of the arrangement in FIG. 3 is the same as that described with reference to FIG. 1 except for replacement of inductor C by pump P.

In accordance with another arrangement, as shown in FIG. 4, the terminal end portion of discharge passage 22 may be provided with a downwardly extending boxlike portion 112 having a discharge orifice 114. A return passageway or conduit 116 may then be connected with box-like member 112 at any desirable level 118 above orifice 114. Return passageway or conduit 116 may then be connected through a sidewall of passageway 22 or directly with receptacle A. Metal transferred to box member 112 either by induction, mechanical pumping or gas pressure then simply returns to receptacle A through return passageway 116 while desirable head 118 is maintained substantially constant. The connection between box member 112 and return passageway 118 may also include an adjustable gate for regulating return flow to adjust predetermined head 118. This arrangement may also be used with the stopper previously described.

Instead of a mechanical pump P for conduit102 of FIG. 3 it will be recognized that it is also possible to surround conduit 102 with an induction coil so that electromagnetic force is still used for supplying metal to discharge orifice 30. It will be recognized that it is also possible to use gas pressure for forcing metal from receptacle A to discharge orifice 30 if excess metal is returned to a separate non-pressurized vessel. Arrangements including more than one receptacle, with one being provided for pouring and the other for return metal are also possible. Arrangements wherein discharge orifice 30 is completely separate from receptacle A are also possible.

Although the invention has been described with reference to a preferred embodiment, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification. The present invention includes all such equivalent alterations and modifications and is limited only by the scope of the claims.

Having thus described my invention, I claim:

1. A method of pouring liquid metal from a receptacle through a discharge orifice, comprising the steps of; transferring metal from said receptacle to said orifice to completely cover said orifice with a substantially predetermined head of liquid metal so that liquid metal flows through said orifice at a substantially constant predetermined rate proportional to said head, continuing to transfer metal from said receptacle to said orifice at a rate in excess of that required to maintain metal flowing through said orifice at said predetermined rate, and returning excess metal to said receptacle at a rate substantially equal to the transfer rate less the predetermined discharge rate, said predetermined head being maintained by returning to the receptacle metal transferred to the orifice in excess of the predetermined discharge rate.

2. The method of claim 1 wherein said orifice includes selectively openable and closable stopper means for selectively opening and closing said orifice to flow of metal therethrough, and further including the step of opening and closing said stopper means at predetermined intervals of time for successively discharging substantially equal predetermined quantities of metal through said orifice.

3. A method of pouring liquid metal from a receptacle having an upwardly inclined discharge passage terminating at a discharge orifice, comprising the steps of:

moving metal from said receptacle upwardly through said discharge passage with an electromagnetic induction field at a sufficient rate to completely cover said discharge orifice with a substantially predetermined head of liquid metal, and maintaining said substantially predetermined head so that metal flows through said orifice at a substantially constant predetermined rate, said step of moving metal from said receptacle upwardly through said discharge passage being carried out at a rate in excess of that required to maintain metal flowing through said orifice at said predetermined rate so that metal in said discharge passage includes a lower level moving upwardly under influence of said induction field and an upper level moving downwardly under influence of gravity, said substantially predetermined head being maintained by having excess metal moved up said passage flow back down in said upper level under influence of gravity.

4. The method of claim 3, and further including the step of alternately energizing and de-energizing said induction field at predetermined intervals of time for successively discharging substantially equal predetermined quantities of metal through said discharge orifice.

5. The method of claim 3, wherein said discharge orifice includes selectively openable and closable stopper means for selectively opening and closing said orifice to flow of metal therethrough, and further including the step of opening and closing said stopper means at predetermined intervals of time for successively discharging substantially equal predetermined quantities of metal through said discharge orifice.

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1. A method of pouring liquid metal from a receptacle through a discharge orifice, comprising the steps of; transferring metal from said receptacle to said orifice to completely cover said orifice with a substantially predetermined head of liquid metal so that liquid metal flows through said orifice at a substantially constant predetermined rate proportional to said head, continuing to transfer metal from said receptacle to said orifice at a rate in excess of that required to maintain metal flowing through said orifice at said predetermined rate, and returning excess metal to said receptacle at a rate substantially equal to the transfer rate less the predetermined discharge rate, said predetermined head being maintained by returning to the receptacle metal transferred to the orifice in excess of the predetermined discharge rate.
 2. The method of claim 1 wherein said orifice includes selectively openable and closable stopper means for selectively opening and closing said orifice to flow of metal therethrough, and further including the step of opening and closing said stopper means at predetermined intervals of time for successively discharging substantially equal predetermined quantities of metal through said orifice.
 3. A method of pouring liquid metal from a receptacle having an upwardly inclined discharge passage terminating at a discharge orifice, comprising the steps of: moving metal from said receptacle upwardly through said discharge passage with an electromagnetic induction field at a sufficient rate to completely cover said discharge orifice with a substantially predetermined head of liquid metal, and maintaining said substantially predetermined head so that metal flows through said orifice at a substantially constant predetermined rate, said step of moving metal from said receptacle upwardly through said discharge passage being carried out at a rate in excess of that required to maintain metal flowing through said orifice at said predetermined rate so that metal in said discharge passage includes a lower level moving upwardly under influence of said induction field and an upper level moving downwardly under influence of gravity, said substantially predetermined head being maintained by having excess metal moved up said passage flow back down in said upper level under influence of gravity.
 4. The method of claim 3, and further including the step of alternately energizing and de-energizing said induction field at predetermined intervals of time for successively discharging substantially equal predetermined quantities of metal through said discharge orifice.
 5. The method of claim 3, wherein said discharge orifice includes selectively openable and closable stopper means for selectively opening and closing said orifice to flow of metal therethrough, and further including the step of opening and closing said stopper means at predetermined intervals of time for successively discharging substantially equal predetermined quantities of metal through said discharge orifice. 